andre, it's gonna take more than the price of a great grill to buy a cab - I feel for ya, seein the pics of yer rust problems - scrapped more than one truck in that condition myself - might you be better off to find a complete truck in better condition than just a cab [looks like ya need doors too!]
I know a guy here on Saltspring Island who could prolly come up w/ a 5-9 GMC cab, but I'd expect him to want around a thou CDN for it, and you'd still hafta get it over there
have you checked w/ Scotts Super Trucks in Alta?
Bill